Production and Spread of the Woolly Aphis Parasite, Aphelinus Mali, in the Hood River Valley

Abstract

From an initial introduction of 550 woolly apple aphis parasites from Michigan in 1929 a total of 92,000 have been reared and liberated in the Hood River Valley and other points. The majority are liberated in the adult stage after being reared in caged apple trees. The parasite is now thoroughly established in over 40 Hood River orchards and is spreading rapidly. Degree of woolly aphis control by the parasite has been demonstrated. Seasonal history of the parasite has been closely checked for two seasons, showing eight complete generations in 1930 and nine in 1931.